Isocyanate-, Isothiocyanate-, Urea-, and Thiourea-Substituted Boron Dipyrromethene Dyes as Fluorescent Probes

Abstract

Boron dipyrromethene dyes (Bodipy) bearing a meso-phenyl substituent carrying a variety of functional groups can be prepared under mild conditions. A single-crystal X-ray structure determination for the 3,5-dinitrophenyl compound shows the phenyl ring to be almost orthogonal (dihedral angle 84 degrees) to the plane of the Bodipy core, with one nitro group almost coplanar with the ring and the other tilted by approximately 21 degrees. Nitro substituents at the 3-, 4-, and 5- positions of the phenyl group are readily reduced to the corresponding amino groups and then converted to isocyanato, isothiocyanato, urea, thiourea, and some polyimine derivatives, the last providing additional functionality (phenazine and pyridylindole units) suitable for chelation of metal ions. All compounds are redox active, the electron-transfer processes being assigned on the basis of comparisons with model compounds. Their fluorescence properties are sensitive to the phenyl group substituents. The Bodipy unit excited state appears to be a strong reductant (Eo approximately -1.4 V) and a modest oxidant (Eo approximately +1.0 V). Quenching processes in the nitro and phenazine derivatives appear to involve intramolecular photoinduced electron transfer.

Selective Triplet‐State Formation during Charge Recombination in a Fullerene/Bodipy Molecular Dyad (Bodipy=Borondipyrromethene)

“…This process can be ascribed to formation of the Bodipy p-radical cation. [35,36] The second peak seen under these conditions is due to oxidation of the C 60 unit (possibly the tertiary amine of the pyrrolidine), and is electrochemically irreversible, with the anodic peak potential being 1.40 V vs. SCE. [37] A series of peaks are seen on reductive scans, but these are easily assigned by comparison with the cyclic voltammogram recorded for the equimolar mixture (Figure 1).…”

Fine‐Tuning of Yellow or Red Photo‐ and Electroluminescence of Functional Difluoro‐boradiazaindacene Films

“…[43] By means of a catalytic hydrogenation over Pd on charcoal, this nitro derivative can be easily reduced into the corresponding amine (Scheme 1). [44] Reaction of the p-aminophenyl-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene derivative with a series of 3,4,5-tris-alkyloxy-benzoic acids leads to the synthesis of a wide range of amido-Bodipy derivatives functionalized with straight or branched paraffin chains.…”

Generating Reactive MILs: Isocyanate‐ and Isothiocyanate‐Bearing MILs through Postsynthetic Modification

“…90 % converted (see below) to isocyanate and isothiocyanate groups, respectively ( Figure 1, designated MIL-53(Al)-NCO and MIL-53(Al)-NCS). The methodology for the conversion of arylamines to iso(thio)cyanates used here is based upon a known solution procedure, [19][20][21][22] but no reports on amine-based solids exist. The choice of solvent was found to be critical, as no conversion was observed in other solvents tested including toluene, benzene, DMSO, CHCl 3 , CH 2 Cl 2 , and CH 3 CN.…”